Source code
Revision control
Copy as Markdown
Other Tools
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#include "Downscaler.h"
#include <algorithm>
#include <ctime>
#include "mozilla/gfx/2D.h"
using std::swap;
namespace mozilla {
using gfx::IntRect;
namespace image {
Downscaler::Downscaler(const nsIntSize& aTargetSize)
: mTargetSize(aTargetSize),
mOutputBuffer(nullptr),
mWindowCapacity(0),
mLinesInBuffer(0),
mPrevInvalidatedLine(0),
mCurrentOutLine(0),
mCurrentInLine(0),
mHasAlpha(true),
mFlipVertically(false) {
MOZ_ASSERT(mTargetSize.width > 0 && mTargetSize.height > 0,
"Invalid target size");
}
Downscaler::~Downscaler() { ReleaseWindow(); }
void Downscaler::ReleaseWindow() {
if (!mWindow) {
return;
}
for (int32_t i = 0; i < mWindowCapacity; ++i) {
delete[] mWindow[i];
}
mWindow = nullptr;
mWindowCapacity = 0;
}
nsresult Downscaler::BeginFrame(const nsIntSize& aOriginalSize,
const Maybe<nsIntRect>& aFrameRect,
uint8_t* aOutputBuffer, bool aHasAlpha,
bool aFlipVertically /* = false */) {
MOZ_ASSERT(aOutputBuffer);
MOZ_ASSERT(mTargetSize != aOriginalSize,
"Created a downscaler, but not downscaling?");
MOZ_ASSERT(mTargetSize.width <= aOriginalSize.width,
"Created a downscaler, but width is larger");
MOZ_ASSERT(mTargetSize.height <= aOriginalSize.height,
"Created a downscaler, but height is larger");
MOZ_ASSERT(aOriginalSize.width > 0 && aOriginalSize.height > 0,
"Invalid original size");
// Only downscale from reasonable sizes to avoid using too much memory/cpu
// downscaling and decoding. 1 << 20 == 1,048,576 seems a reasonable limit.
if (aOriginalSize.width > (1 << 20) || aOriginalSize.height > (1 << 20)) {
NS_WARNING("Trying to downscale image frame that is too large");
return NS_ERROR_INVALID_ARG;
}
mFrameRect = aFrameRect.valueOr(nsIntRect(nsIntPoint(), aOriginalSize));
MOZ_ASSERT(mFrameRect.X() >= 0 && mFrameRect.Y() >= 0 &&
mFrameRect.Width() >= 0 && mFrameRect.Height() >= 0,
"Frame rect must have non-negative components");
MOZ_ASSERT(nsIntRect(0, 0, aOriginalSize.width, aOriginalSize.height)
.Contains(mFrameRect),
"Frame rect must fit inside image");
MOZ_ASSERT_IF(!nsIntRect(0, 0, aOriginalSize.width, aOriginalSize.height)
.IsEqualEdges(mFrameRect),
aHasAlpha);
mOriginalSize = aOriginalSize;
mScale = gfx::MatrixScalesDouble(
double(mOriginalSize.width) / mTargetSize.width,
double(mOriginalSize.height) / mTargetSize.height);
mOutputBuffer = aOutputBuffer;
mHasAlpha = aHasAlpha;
mFlipVertically = aFlipVertically;
ReleaseWindow();
auto resizeMethod = gfx::ConvolutionFilter::ResizeMethod::LANCZOS3;
if (!mXFilter.ComputeResizeFilter(resizeMethod, mOriginalSize.width,
mTargetSize.width) ||
!mYFilter.ComputeResizeFilter(resizeMethod, mOriginalSize.height,
mTargetSize.height)) {
NS_WARNING("Failed to compute filters for image downscaling");
return NS_ERROR_OUT_OF_MEMORY;
}
// Allocate the buffer, which contains scanlines of the original image.
// pad to handle overreads by the simd code
size_t bufferLen = gfx::ConvolutionFilter::PadBytesForSIMD(
mOriginalSize.width * sizeof(uint32_t));
mRowBuffer.reset(new (fallible) uint8_t[bufferLen]);
if (MOZ_UNLIKELY(!mRowBuffer)) {
return NS_ERROR_OUT_OF_MEMORY;
}
// Zero buffer to keep valgrind happy.
memset(mRowBuffer.get(), 0, bufferLen);
// Allocate the window, which contains horizontally downscaled scanlines. (We
// can store scanlines which are already downscale because our downscaling
// filter is separable.)
mWindowCapacity = mYFilter.MaxFilter();
mWindow.reset(new (fallible) uint8_t*[mWindowCapacity]);
if (MOZ_UNLIKELY(!mWindow)) {
return NS_ERROR_OUT_OF_MEMORY;
}
bool anyAllocationFailed = false;
// pad to handle overreads by the simd code
const size_t rowSize = gfx::ConvolutionFilter::PadBytesForSIMD(
mTargetSize.width * sizeof(uint32_t));
for (int32_t i = 0; i < mWindowCapacity; ++i) {
mWindow[i] = new (fallible) uint8_t[rowSize];
anyAllocationFailed = anyAllocationFailed || mWindow[i] == nullptr;
}
if (MOZ_UNLIKELY(anyAllocationFailed)) {
// We intentionally iterate through the entire array even if an allocation
// fails, to ensure that all the pointers in it are either valid or nullptr.
// That in turn ensures that ReleaseWindow() can clean up correctly.
return NS_ERROR_OUT_OF_MEMORY;
}
ResetForNextProgressivePass();
return NS_OK;
}
void Downscaler::SkipToRow(int32_t aRow) {
if (mCurrentInLine < aRow) {
ClearRow();
do {
CommitRow();
} while (mCurrentInLine < aRow);
}
}
void Downscaler::ResetForNextProgressivePass() {
mPrevInvalidatedLine = 0;
mCurrentOutLine = 0;
mCurrentInLine = 0;
mLinesInBuffer = 0;
if (mFrameRect.IsEmpty()) {
// Our frame rect is zero size; commit rows until the end of the image.
SkipToRow(mOriginalSize.height - 1);
} else {
// If we have a vertical offset, commit rows to shift us past it.
SkipToRow(mFrameRect.Y());
}
}
void Downscaler::ClearRestOfRow(uint32_t aStartingAtCol) {
MOZ_ASSERT(int64_t(aStartingAtCol) <= int64_t(mOriginalSize.width));
uint32_t bytesToClear =
(mOriginalSize.width - aStartingAtCol) * sizeof(uint32_t);
memset(mRowBuffer.get() + (aStartingAtCol * sizeof(uint32_t)), 0,
bytesToClear);
}
void Downscaler::CommitRow() {
MOZ_ASSERT(mOutputBuffer, "Should have a current frame");
MOZ_ASSERT(mCurrentInLine < mOriginalSize.height, "Past end of input");
if (mCurrentOutLine < mTargetSize.height) {
int32_t filterOffset = 0;
int32_t filterLength = 0;
mYFilter.GetFilterOffsetAndLength(mCurrentOutLine, &filterOffset,
&filterLength);
int32_t inLineToRead = filterOffset + mLinesInBuffer;
MOZ_ASSERT(mCurrentInLine <= inLineToRead, "Reading past end of input");
if (mCurrentInLine == inLineToRead) {
MOZ_RELEASE_ASSERT(mLinesInBuffer < mWindowCapacity,
"Need more rows than capacity!");
mXFilter.ConvolveHorizontally(mRowBuffer.get(), mWindow[mLinesInBuffer++],
mHasAlpha);
}
MOZ_ASSERT(mCurrentOutLine < mTargetSize.height,
"Writing past end of output");
while (mLinesInBuffer >= filterLength) {
DownscaleInputLine();
if (mCurrentOutLine == mTargetSize.height) {
break; // We're done.
}
mYFilter.GetFilterOffsetAndLength(mCurrentOutLine, &filterOffset,
&filterLength);
}
}
mCurrentInLine += 1;
// If we're at the end of the part of the original image that has data, commit
// rows to shift us to the end.
if (mCurrentInLine == (mFrameRect.Y() + mFrameRect.Height())) {
SkipToRow(mOriginalSize.height - 1);
}
}
bool Downscaler::HasInvalidation() const {
return mCurrentOutLine > mPrevInvalidatedLine;
}
DownscalerInvalidRect Downscaler::TakeInvalidRect() {
if (MOZ_UNLIKELY(!HasInvalidation())) {
return DownscalerInvalidRect();
}
DownscalerInvalidRect invalidRect;
// Compute the target size invalid rect.
if (mFlipVertically) {
// We need to flip it. This will implicitly flip the original size invalid
// rect, since we compute it by scaling this rect.
invalidRect.mTargetSizeRect =
IntRect(0, mTargetSize.height - mCurrentOutLine, mTargetSize.width,
mCurrentOutLine - mPrevInvalidatedLine);
} else {
invalidRect.mTargetSizeRect =
IntRect(0, mPrevInvalidatedLine, mTargetSize.width,
mCurrentOutLine - mPrevInvalidatedLine);
}
mPrevInvalidatedLine = mCurrentOutLine;
// Compute the original size invalid rect.
invalidRect.mOriginalSizeRect = invalidRect.mTargetSizeRect;
invalidRect.mOriginalSizeRect.ScaleRoundOut(mScale.xScale, mScale.yScale);
return invalidRect;
}
void Downscaler::DownscaleInputLine() {
MOZ_ASSERT(mOutputBuffer);
MOZ_ASSERT(mCurrentOutLine < mTargetSize.height,
"Writing past end of output");
int32_t filterOffset = 0;
int32_t filterLength = 0;
mYFilter.GetFilterOffsetAndLength(mCurrentOutLine, &filterOffset,
&filterLength);
int32_t currentOutLine = mFlipVertically
? mTargetSize.height - (mCurrentOutLine + 1)
: mCurrentOutLine;
MOZ_ASSERT(currentOutLine >= 0);
uint8_t* outputLine =
&mOutputBuffer[currentOutLine * mTargetSize.width * sizeof(uint32_t)];
mYFilter.ConvolveVertically(mWindow.get(), outputLine, mCurrentOutLine,
mXFilter.NumValues(), mHasAlpha);
mCurrentOutLine += 1;
if (mCurrentOutLine == mTargetSize.height) {
// We're done.
return;
}
int32_t newFilterOffset = 0;
int32_t newFilterLength = 0;
mYFilter.GetFilterOffsetAndLength(mCurrentOutLine, &newFilterOffset,
&newFilterLength);
int diff = newFilterOffset - filterOffset;
MOZ_ASSERT(diff >= 0, "Moving backwards in the filter?");
// Shift the buffer. We're just moving pointers here, so this is cheap.
mLinesInBuffer -= diff;
mLinesInBuffer = std::min(std::max(mLinesInBuffer, 0), mWindowCapacity);
// If we already have enough rows to satisfy the filter, there is no need
// to swap as we won't be writing more before the next convolution.
if (filterLength > mLinesInBuffer) {
for (int32_t i = 0; i < mLinesInBuffer; ++i) {
swap(mWindow[i], mWindow[filterLength - mLinesInBuffer + i]);
}
}
}
} // namespace image
} // namespace mozilla